Bullet containment trap with a modular backstop

ABSTRACT

A bullet containment trap ( 1 ) with a modular backstop ( 7 ) is disclosed. The device ( 1 ) with the modular backstop ( 7 ) comprises of at least one open ended bullet receiving chamber ( 4 ), at least one electronic target assembly (not shown) configured to project at least one target placed at a rear end of the said open-ended bullet receiving chamber ( 4 ). The bullet fired compasses the said bullet receiving chamber ( 04 ) while in contact with boundary wall and enters a terminal part of said boundary wall over a throat ( 6 ) of a passageway and moves through said throat ( 6 ) to dissipate on hitting a modular backstop ( 7 ) of a deceleration chamber ( 5 ). The said modular backstop ( 7 ) with at least two impact zones are made by stacking multiple individual armored plates ( 12 ) vertically and/or horizontally in to a plurality of cassettes ( 11 ), wherein the said cassettes and/or the individual armored plates ( 12 ) within each of the said cassettes ( 11 ) are all replaceable for deformation.

TECHNICAL FIELD OF THE INVENTION

The invention relates to a bullet containment trap that is used forsecuring used bullets while dry firing practice. Specifically, theinvention relates to a bullet containment trap used in conjunction witha Containerized Tubular Shooting Range (CTSR) that is used for trainingpurposes.

BACKGROUND OF THE INVENTION

Bullet containment traps per se are well known devices which are usedfor many years in firing ranges. These devices are usually devised at arelatively short distance from the shooter to catch the waste lead,brass and jacket material of the bullet being fired and prevent eitherthe ricochet of a whole bullet or a large fragment thereof. A furtherobject of the device is to provide protection against back splatteringof numerous small metal particles, which could return with enough energyto cause injury to the shooter or an innocent bystander.

EP0683375A1 discloses a bullet containment trap with an elementinsertable within a container. All walls apart from the wall facingshooters are constituted of ballistic plates. The surface of the bulletarresting element facing shooters is constituted of a rubber cover. Italso discloses a layer that allows the passage of a non-deformed bullet.It is claimed that the said layer does not break or permanently deformafter the passage of the bullet.

U.S. Pat. No. 385,546A discloses another bullet containment trap with aplate projecting from the wall of a chamber and inclined at an acuteangle to the path of the bullet. The plate is placed in such position inrelation to the target that bullet which have passed through the targetstrike the plate and are thereby deflected and slide along its surfaceand into the chamber, and continue to circulate around the chamber untiltheir energy of motion is expended, when they drop into a receptaclesuitably placed.

U.S. Pat. No. 4,126,311A discloses another bullet containment trap withan entry funnel with a throat of gradually reduced dimension, the funnelbeing tangentially secured to a tubular tank. A mouth at an exit end ofthe funnel throat is aligned with an opening in the tank to directbullet from the throat into the tank. The tank is closed at its top, andits open bottom is connected to a cone, the cone being of reduceddiameter from its point of connection at the tank to its exit aperture.The cone interior may be corrugated to aid in disintegration of thebullet as the bullet expends its travel energy in rotation therein.

U.S. Pat. No. 5,121,671A discloses another bullet containment trap thatincludes a passageway bounded by upper and lower flat plates. Thepassageway has an entrance opening and a shallow exit opening or throat,and a generally spiral-walled spent bullet energy-dissipating chamberhaving a horizontal axis communicates substantially tangentially withthe passageway through the throat.

U.S. Pat. No. 5,259,291 discloses another bullet containment trap forreceiving a bullet travelling along a substantially horizontal axis oftravel at high velocity includes a pair of side walls, a primary,secondary and tertiary deflecting plates. A second primary plate affordsa trap of significantly less depth than the trap without such a platefor traps having substantially the same size rectangular mouth. Ineither embodiment, a tray along the back of the trap collects thetrapped bullet or particles thereof.

U.S. Pat. No. 5,400,692 discloses another bullet containment trap forstopping the forward momentum of bullet traveling in a generallyhorizontal zone of bullet travel. There are side plates on the chamberwhich combine with the other structure to confine bullet, fragments andparticulate matter to the chamber until inertial momentum is arrestedand the bullet drops out of an egress.

U.S. Pat. No. 5,456,155 discloses another bullet containment trap in anindoor range having a first end and a second end by use of a bullettrap. The bullet trap is formed from an upper plate and a lower plateand a liquid-filled trough. The bullet trap is positioned near thesecond end of the indoor range. The upper plate preferably curvesdownwardly between the slot and the second end of the range and ends ina generally vertically downward orientation pointed toward the liquidfilled trough. Bullets fired into the bullet trap from the first end ofthe range pass through the slot and are trapped in the liquid filledtrough.

U.S. Pat. No. 5,535,662 discloses another bullet trap that utilizesangled impact plates to decelerate bullet. Once the bullet had slowedsufficiently, they would fall into a canister mounted below thecontainment chamber.

JP3806878B2 discloses another bullet trap that is arranged behind atarget of actual shooting of a firearm and captures a bullet firedtoward the target by a granular member. In this case, the stoppingdevice may be continuously provided so as to surround the archer andbend in a plane.

US2006/0131813 discloses another bullet trap for installation atshooting ranges. The device has a housing, which housing has an L-shapedconcrete plate, a resilient top layer and a flexible bottom layer. Theinclined bottom surface is inclined at an angle in relation to ahorizontal plane. The angle is less than an angle of repose of thegranular material.

US20140346734A1 discloses another bullet trap for decelerating bulletincluding a housing and bullet deceleration material disposed within thehousing. The bullet deceleration material may include a plurality oflayers of rubber material and metal for safely decelerating a bullet.The bullet trap may also include vent holes for dissipation of the forcegenerated from discharging a firearm in the housing and diverters whichchannel vented gasses away from a shooter.

US20150184985A1 discloses another bullet trap with tapered shootinglanes or zones. The shooting lanes are wider at the position of theshooter than they are at the end of the range, thereby resulting in adesign that is cheaper to build and easier to maintain. The tapering ofthe lanes can be in the horizontal or vertical directions (or both).This design can be used in indoor or outdoor ranges, with firearms,bows, crossbows, air rifles, air softs, and other types of bullet thatare fired, shot, or launched.

U.S. Pat. No. 9,733,050B2 discloses another bullet trap comprising afoundation constituting a floor and a rear wall of the bullet arrestingdevice. It further comprises partition walls extending in a directionsubstantially perpendicular to the rear wall, wherein the partitionwalls comprise a rear edge connected to the foundation, and a frontedge. In it, the spent bullet penetrates a hollow section expand throughthe stopping material so that the bullet will be captured between therow of hollow sections and the rear wall.

U.S. Pat. No. 7,194,944 discloses another bullet trap formed withoutintervening sidewalls to enable cross-shooting and the like with reducedrisk or ricochet or damage to the bullet trap. Furthermore, the bullettrap can be configured in a variety of ways to eliminate the need forfacing plates while providing a removable attachment mechanism, toenable repair on the trap, to reduce bullet adhesion to the trap and toprovide improved containment of lead and improved access to the trap.

All of the above bullet containment traps suffer from the same commonproblem. Specifically, the side walls limit the ability of the bullet totravel laterally straight ahead; and damages the backstop and the sideplates.

In addition to the above, many of the prior art bullet containment trapshave problems with bullet sticking to the deceleration plates. ThoughU.S. Pat. No. 7,194,944 discloses reduced bullet adhesion to the trapand claims to provide improved containment of lead and improved accessto the trap. The chamber becomes damaged or needs maintenance or repairwork, and it is still difficult to access the interior of the trap.

Prior art bullet containment traps are all proposed for short range dryfiring practice. The back plates of these containment traps are alldesigned and can withstand only subsonic projectiles and not supersonic.Inventors felt a dire need for an improved bullet containment trap forshort range dry firing practice wherein it withstands both subsonic andsupersonic projectiles.

BRIEF SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improved bulletcontainment trap.

It is another object of the present invention to provide a bulletcontainment trap with a very strong backstop structure that lasts longand provides better access to the interior of the trap.

Another object of the present invention is that the backstop has amodular structure wherein the damaged plates can be easily changed.

Other key objectives of the present invention is to withstand more than1 million shots with negligible deformation or damage to the backstopand its armored plates. It is primarily desired that the improved bulletcontainment trap consists a very strong backstop structure that lastslong and provides better access to the interior of the trap. It is alsodesired that the backstop has a modular structure wherein the damagedplates can be easily changed and the whole of the bullet containmenttrap combined with the modular backstop and/or the modular backstopalone is easily movable and adaptable for indoor and outdoor use.

According to a first aspect of the present invention, a bulletcontainment trap device with a modular backstop is disclosed. The devicecomprises of at least one open ended bullet receiving chamber, at leastone electronic target assembly configured to project at least one targetplaced at a rear end of the open-ended bullet receiving chamber.

In accordance with the first aspect of the present invention, the devicealso comprises of a boundary wall means for resisting penetration ofbullet and to inhibit rebounding of bullet there from.

In accordance with the first aspect of the present invention, the devicefurther comprises of a plurality of supporting frames for holding thebullet receiving chamber and the said boundary wall means.

In accordance with the first aspect of the present invention, the saidboundary wall means is backed with a bullet's deceleration chamber in ahorizontal axis, wherein the bullet fired compasses the bullet receivingchamber while in contact with said boundary wall and enters a terminalpart of said boundary wall over a throat of a passageway and movesthrough said throat to dissipate on hitting a modular backstop of thesaid deceleration chamber.

In accordance with the first aspect of the present invention, the saidmodular backstop comprises a first impact zone circumferentiallyoriented at a first angle from the horizontal zone of bullet travel andextends to at least one successive impact zone.

In accordance with the first aspect of the present invention, the saidmodular backstops with at least two impact zones are made by stackingmultiple individual armored plates vertically and/or horizontally in toa plurality of cassettes.

In accordance with the first aspect of the present invention, the saidcassettes formed by stacking multiple individual armored plates are heldvertically and/or horizontally to form the said modular backstop,wherein the said cassettes are held with long bolts making the impingingloads of the bullet hitting the said backstop distributed to multipleindividual plates of the said cassettes closely stacked.

In accordance with the first aspect of the present invention, the saidcassettes have configurable armored plates and each plate has aconfigurable size, the said armored plates are screwed with two bolts toengaged and remove the cassette after damage.

In accordance with the first aspect of the present invention, the saidcassettes and/or the individual armored plates within each of the saidcassettes are all replaceable for deformation.

In accordance with the first aspect of the present invention, the saiddevice is used for de-energizing and collecting the bullet fired along asubstantially horizontal path of flight.

In accordance with the first aspect of the present invention, the saidbullet that enters the said deceleration chamber, even at a relativelylow angle will move along the chamber without being shattered ordamaging the walls or the modular backstop.

In accordance with the first aspect of the present invention, the spentbullet ultimately falls off the modular backstop, and are flushed into apassageway and then into a collecting vessel.

In accordance with the first aspect of the present invention, the saidmodular backstop comprises very high flexural bending strength comparedto multilayered backstops.

In accordance with the first aspect of the present invention, the saidcassettes vertically held with support of long bolts increases thecompressive force making all the stacked plates behave like a singlelumped block.

In accordance with the first aspect of the present invention, thedeformation point is not constrained to single location on the modularbackstop of the device, but is distributed to locations which are atconsiderable distance.

According to a second aspect of the present invention, a method ofreplacing cassettes and/or the individual armored plates for deformationof the modular backstop of the said bullet containment trap device isdisclosed.

In accordance with the second aspect of the present invention, themethod comprises a first step of removing a plurality of long bolts thatlocks a plurality of cassettes formed of stacking multiple individualarmored plates vertically and/or horizontally. The said method comprisesa second step of removing a back plate and a plurality of side plates toget access to the said cassettes. The said method comprises a third stepof identifying a damaged cassette from the lumped block to repair andreplace the damaged cassette and/or the individual armored plates.

In accordance with the second aspect of the present invention, themethod comprises a fourth step of removing a plurality of cassettelocking bolts to remove damaged armored plates of the said cassettes.

In accordance with the second aspect of the present invention, themodular backstop of the said bullet containment trap device (allowscassettes and/or the individual armored plates within each of the saidcassettes to be easily replaced and/or repaired for deformation.

In accordance with the second aspect of the present invention, thedevice is devised at a relatively short distance from the shooter tocatch the waste lead, brass and jacket material of the bullet beingfired and prevent either the ricochet of a whole bullet or a largefragment thereof.

Considerable concern is the lead contained in a bullet. A considerableamount of lead could be released into the environment, thereby injuringwildlife and contaminating groundwater supplies. The present inventioncontemplates reuse of the lead and makes the device environmentalfriendly.

Conventionally rubber layer is used along with the back plates. Themodular backstop of the present invention completely avoids usage ofrubber.

Consumables like the rubber sheets that are usually used and are to bechanged frequently is avoided; back plates that are to be replaced fordeformation and damage are minimized.

Material (steel) used is less due to the shape and size of the modularbackstop designed on finding an accurate velocity degradation curve ofthe projectile being dissipated.

The bullet containment trap with the modular backstop is adapted to beused in indoor ranges, outdoor ranges, along with containerized tubularshooting ranges, in containerized modular ranges, and as a portable dryfiring shooting range.

Expandable and extendable to multiuser, multiple training ranges with atrainer console.

Economic significance to users as it withstands more than 1 millionsubsonic and supersonic shots used along with different dry practiceshooting ranges.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the inventionwill become apparent from a consideration of the following detaileddescription presented in connection with the accompanying drawings inwhich:

FIG. 1 illustrates a perspective of a bullet containment trap with amodular backstop, according to an exemplary embodiment of the presentinvention;

FIG. 2 a illustrates a top sectional view of the deceleration chamberthat comprises of the said modular backstop according to the exemplaryembodiment of the present invention;

FIG. 2 b illustrates a half sectional view of the deceleration chamberaccording to the exemplary embodiment of the present invention;

FIG. 2 c illustrates a front view of a cassette, according to theexemplary embodiment of the present invention;

FIG. 3 a illustrates a material characteristic of a bullet for steelcore, according to the exemplary embodiment of the present invention;

FIG. 3 b illustrates a material characteristic of the bullet for steeljacket, according to the exemplary embodiment of the present invention.

FIG. 3 c illustrates a moderate strain rate compression test results forsteel core and steel jacket, according to the exemplary embodiment ofthe present invention;

FIG. 3 d illustrates a strain comparison for steel core and steeljacket, according to the exemplary embodiment of the present invention;

FIG. 4 a-4 b illustrates a velocity degradation of bullets, according tothe exemplary embodiment of the present invention;

FIG. 5 illustrates a exploded side view of the said modular backstopaccording to the exemplary embodiment of the present invention;

It is appreciated that not all aspects and structures of the presentinvention are visible in a single drawing, and as such multiple views ofthe invention are presented so as to clearly show the structures of theinvention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a bullet containment trap for securingused bullets. Specifically, the invention relates to bullet containmenttraps, be used in conjunction with Containerized Tubular Shooting Range(CTSR) that is used for training purposes.

According to an exemplary embodiment of the present invention, a bulletcontainment trap with a modular backstop system for securing usedbullets is disclosed. The said modular backstop system comprises of atleast one electronic target assembly (not shown) configured to projectat least one target placed at a rear end of an open-ended bulletreceiving chamber. The said bullet receiving chamber is supported by aplurality of supporting frames. The said bullet receiving chamber isbacked with a bullet's deceleration chamber in a horizontal axis whereinthe bullet that is fired compasses the bullet receiving chamber while incontact with a plurality of boundary walls and enters a terminal part ofsaid boundary wall over a throat of a passageway and moves through saidthroat to dissipate on hitting a modular backstop of the saiddeceleration chamber.

In accordance with the exemplary embodiment of the present invention,the said modular backstop with at least two impact zones is made bystacking multiple individual armored plates vertically and/orhorizontally in to a plurality of cassettes.

In accordance with the exemplary embodiment of the present invention,the said modular backstop comprises a first impact zonecircumferentially oriented at a first angle from the horizontal zone ofbullet travel and extends to at least one successive impact zone.

In accordance with the exemplary embodiment of the present invention,the said cassettes formed by stacking multiple individual armored platesare held vertically and/or horizontally to form the said modularbackstop, wherein the said cassettes are joined with long bolts makingthe impinging loads of the bullet hitting the said backstop distributedto multiple individual plates of the said cassettes closely stacked. Thesaid cassettes and/or the individual armored plates within each of thesaid cassettes are all replaceable for deformation.

In accordance with the exemplary embodiment of the present invention,the said device is used for de-energizing and collecting the bulletfired along a substantially horizontal path of flight. The said bulletthat enters the said deceleration chamber, even at a relatively lowangle will move along the chamber without being shattered or damagingthe walls or the modular backstop.

In accordance with the exemplary embodiment of the present invention,the device can also be rotated to be used in horizontal position byjoining number of devices to form a larger device which can be used inboth inside and outside ranges.

In accordance with the exemplary embodiment of the present invention,the spent bullet ultimately falls off the modular backstop, and areflushed into a passageway and then into a collecting vessel. the modularbackstop comprises very high flexural bending strength compared tomultilayered backstops.

In accordance with the exemplary embodiment of the present invention,the said cassettes vertically held with support of long bolts increasesthe compressive force making all the stacked plates behave like a singlelumped block. The deformation point is not constrained to singlelocation on the modular backstop of the device, but is distributed tolocations which are at considerable distance. The said cassettes haveconfigurable armored plates and each plate has a configurable size.

According to the exemplary embodiment of the present invention, a methodof replacing cassettes and/or the individual armored plates fordeformation of the modular backstop of the said bullet containment trapdevice is disclosed.

In accordance with the exemplary embodiment of the present invention,the method comprises a first step of removing a plurality of long boltsthat locks a plurality of cassettes formed of stacking multipleindividual armored plates vertically and/or horizontally. The saidmethod comprises a second step of removing a back plate and a pluralityof side plates to get access to the said cassettes. The said methodcomprises a third step of identifying a damaged cassette from the lumpedblock to repair and replace the damaged cassette and/or the individualarmored plates.

In accordance with the exemplary embodiment of the present invention,the method comprises a fourth step of removing a plurality of cassettelocking bolts to remove damaged armored plates of the said cassettes.

In accordance with the exemplary embodiment of the present invention,the modular backstop of the said bullet containment trap device (allowscassettes and/or the individual armored plates within each of the saidcassettes to be easily replaced and/or repaired for deformation.

Reference will now be made to the drawings in which the various elementsof the present invention will be given numeral designations and in whichthe invention will be discussed so as to enable one skilled in the artto make and use the invention. It is to be understood that the followingdescription is only exemplary of the principles of the presentinvention, and should not be viewed as narrowing the pending claims.Additionally, it should be appreciated that the components of theindividual embodiments discussed may be selectively combined inaccordance with the teachings of the present disclosure. Furthermore, itshould be appreciated that various embodiments will accomplish differentobjects of the invention, and that some embodiments falling within thescope of the invention may not accomplish all of the advantages orobjects which other embodiments may achieve.

Referring to FIG. 1 , the device (1) with a modular backstop (7) inaccordance with an exemplary embodiment of the present invention isdisclosed. The device (1) comprises of a bullet receiving chamber (4)for resisting penetration of bullet and to inhibit rebounding of bullet.The device (1) comprises of a top plate, bottom plate, and left andright plate placed in a rectangular shape to form an open-ended bulletreceiving chamber (4), and a deceleration chamber (5), placed at a rearend of the open-ended bullet receiving chamber (4).

The said bullet receiving chamber (4) and deceleration chamber (5) ismounted in between supporting frames top (2) and bottom frame (3) with awheel (4) and a collecting vessel (not shown) is placed below thedeceleration chamber (5). The said bullet receiving chamber (4) means isbacked with a bullet's deceleration chamber (5) in a horizontal axis.

Referring to FIG. 2 a-2 b the deceleration chamber (5) in accordancewith the exemplary embodiment of the present invention is disclosed. Thedeceleration chamber (5) comprises of modular backstop (7), a pluralityof cassettes (11) placed vertically and locked both sides with a nut (8)along with a back top fixing plate (9). A left and right impact platesare placed beside the modular backstop (7) to compass the bullet in itsaxis. Wherein the said back top fixing plate (10) also comprises of longvertical impact plates (15) are fixed at an angle in at least as greatas the secondary angle which is placed on the top and bottom of thecassettes (11).

The bullet fired compasses the bullet receiving chamber (4) while incontact with boundary wall and enters a terminal part of said boundarywall over a throat (6) of a passageway and moves through said throat todissipate on hitting a modular backstop (7) of the said decelerationchamber (5).

Referring to FIG. 2 c the cassettes (11) in accordance with theexemplary embodiment of the present invention is disclosed. The cassette(11) comprises of individual armored plates (12) held vertically and/orhorizontally to form the said modular backstop (7). Wherein, the saidcassettes (11) are formed by stacking multiple individual armored plates(12) vertically and/or horizontally to form the said modular backstop(7). The said cassettes (11) are joined with long bolts (8) making theimpinging loads of the bullet hitting the said backstop (7) distributedto multiple individual plates of the said cassettes (11) closelystacked.

Wherein the said cassette has configurable armored plates (12) and eachplate has a configurable size, and is screwed with two bolts to engagedand remove cassette after damage. The said cassettes (11) and/or theindividual armored plates (12) within each of the said cassettes (11)are all replaceable for deformation.

Referring to FIG. 3 a , the material characteristics of bullet inaccordance with the exemplary embodiment of the present invention isdisclosed. The yield stress of the material is specified as a functionof the equivalent plastic strain at different equivalent plastic strainrates. The material definition also includes failure models withprogressive damage, which causes analysis software to remove elementsfrom the mesh as they fail. Both the ductile and shear initiationcriteria are used: the ductile criterion is specified in terms of theplastic strain at the onset of damage as a tabular function of thestress tri-axiality. The shear criterion is specified in terms of theplastic strain at the onset of damage as a tabular function of the shearstress ratio. The damage evolution energy is assumed to be 500 N/m. Thearmored plate of 10 mm thickness, a bullet of 33 mm in length and 7.82mm diameter has an initial speed of 850 m/sec.

A 3D model of the device (1) is analyzed to understand the structuralbehavior for different bullet impacts in which 3 case studies were done.The armor plate and associated parts of device were assigned with AR500material and bullet material properties were assigned with three corematerial like copper coated steel jacket, lead-antimony and steel.

A bullet fired from the center of the throat (Bulls Eye) in accordancewith the exemplary embodiment of the present invention is shown. Duringthe analysis elements from both bodies fail, which calls for the use ofelement-based surfaces that can adapt to the exposed surfaces of thecurrent non-failed elements. The general contact algorithm supportselement-based surfaces that evolve in this manner (whereas the contactpair algorithm does not). To model eroding contact, we must include inthe contact domain all surface faces that may become exposed during theanalysis, including faces that are originally in the interior of bodies.Only the interior faces that are expected to participate in contact areincluded in the contact domain in this analysis to minimize the memoryuse (including interior faces for all elements in the model would morethan double the memory use).

By default, the general contact algorithm does not include nodalerosion, so contact nodes will still take part in the contactcalculations even after all of the surrounding elements have failed.These nodes act as free-floating point masses that can experiencecontact with the active contact faces. The analysis is conductedincluding nodal erosion, which causes the nodes to be removed from thecontact calculations once all surrounding elements have failed.

Material Characteristics of Bullet: a compression test of steel beingused in accordance with the exemplary embodiment of the presentinvention is shown. Three different regimes of material's response tocompression can be distinguished. After first, elastic response, withthe modulus of elasticity of E1=31.72 GPa, and yield point of σy=362MPa, there are two strain hardening zones with stiffness of E2=1.24 GPaand E3=3.45 GPa, respectively, ending by load increase due toplaten-to-platen compression.

Material Characteristics of Bullet: Referring FIG. 3 b , compressiontest results of a copper plated steel jacket in accordance with theexemplary embodiment of the present invention is shown. Jacket showed tobe stiffer, having Young's modulus of E=42.5 GPa as well as higher yieldstrength of σy=603.3 MPa, then steel core. During compression,cylindrical test sample, after reaching the yield point, gets crushedincluding two buckling modes, indicated by two peaks on the graph.

Referring FIG. 3 c to 3d, test results for stress and strain of a copperplated steel jacket and steel core, Compared, quasi-static and moderatestrain rate compression results, for both bullet core and jacket (FIG. 3d-3 e show initially stiffer response (marked on graphs) of both coreand jacket at higher strain rate. However, it has to be noted that evenmoderate strain rate of 100 s⁻¹ is still much lower than strain ratesthat bullet materials experience during ballistic event, which are inorder of 10,000 s⁻¹.

These above material characteristics were used for Bullet in our devicesimulation to know the strength of the armored plate. Materialcharacteristics were evaluated by doing above physical tests with highstrain rates in dynamic condition.

Bullet Material Properties

Johnson - cook plasticity material model Bullet Component A [MPa] B[MPa]N M C 7.62*39 mm MSC - core 234.4 413.8 0.25 1.03 0.00333 7.62*39 mmMSC - jacket 448.2 303.4 0.15 1.03 0.00333 Lead filler 10.3 41.3 0.211.03 0.00333

Johnson - cook dynamic failure model Bullet Component D1 D2 D3 D4 D5Steel core 5.625 0.3 −7.2 −0.0123 0 7.62*39 mm MSC - jacket 2.25 0.0005−3.6 −0.0123 0 Lead filler 0.25 0 0 0 0

-   -   Damage Evolution type displacement=0.0001    -   Mie-gruneise equation of state (used on all the materials)    -   c_(o)=4.596E6 mm/s    -   s=1.4    -   r_(o)=1.93    -   Linear elastic shear modulus G=9.446E3 MPa

Armor Plate Material Properties

-   -   Density=7800 Kg/m³    -   Elastic Modulus=210 GPa    -   Poisson's Ratio=0.28    -   Yield Strength=776 Mpa    -   Ultimate Tensile Strength=1810 MPa

Assumptions for the Analysis:

-   -   AR-500 Material properties are assigned for DEVICE.    -   Copper coated steel jacket and Lead-Antimony material properties        were applied to the bullet.    -   A non-linear dynamic analysis was performed to account for        nonlinearity in the geometry and material. As it is a transient        non-linear dynamic analysis inertial effects and whole kinetic        energy of the bullet load will be applied and response will be        calculated for every micro second.    -   Steel coated copper jacket lead material are modeled in such a        way that they have proper nodal connectivity between them.    -   Bullet mass of 11.5 g and velocity of 850 m/s was considered    -   Stresses are presented after removing spurious areas.    -   Coefficient of friction was assumed as 0.2 between bullet and        the device.

Analysis is performed by assuming an ideal condition in which no airgaps will be there and strength of the armor plate is analyzed for idealconditions. But in field conditions there will be air traps or distortedcrystal lattice structure at some locations of the components which willdegrade the stiffness of the part causing fatigue failure while inoperating conditions.

Mathematical Material Model Material Constitutive Model

In general, the response of material under High-speed impact involvesconsideration of the effect of strain. Strain rate and temperature.

The Johnson-Cook material model with strain rate dependence was used inthe simulation to define the inelastic behavior of die bullet materials.

The static yield stress σ⁰ is assumed to be of the form

σ⁰ =[A+B(ε^(−pl))n](1−{circumflex over (θ)}^(m))

Where ε^(−pl) is the equivalent plastic strain and A, B, n and m arematerial parameters measured at or below the transition temperatureθ_(transition) {circumflex over (θ)} is the non-dimensional temperaturedefined as

$\hat{\theta} = \begin{Bmatrix}\left. 0\rightarrow{\theta < \theta_{transition}} \right. \\\left. \frac{\left( {\theta - \theta_{transaction}} \right)}{\left( {\theta_{melt} - \theta_{transition}} \right)}\rightarrow{\theta_{transition} \leq \theta \leq \theta_{melt}} \right. \\\left. 1\rightarrow{\theta > \theta_{melt}} \right.\end{Bmatrix}$

Where θ is the current temperature, θ_(melt) is the melt temperature andθ_(transition) is the transition temperature defined as the one at orbelow which there is no temperature dependence on the expression of theyield stress.

${\overset{\_}{\sigma} = {{\sigma^{0}\left( {\varepsilon^{pl},\theta} \right)}{R\left( {\overset{.}{\varepsilon}}^{- {pl}} \right)}}}{{\overset{.}{\varepsilon}}^{- {pl}} = {{{\overset{.}{\varepsilon}}_{0}{\exp\left\lbrack {\frac{1}{c}\left( {R - 1} \right)} \right\rbrack}{for}\overset{\_}{\sigma}} \geq \sigma^{0}}}$

The Johnson-Cook strain rate dependence assumes that

-   -   Where,    -   σ: yield stress at nonzero strain rate    -   {dot over (ε)}^(−pl): equivalent plastic strain rate    -   {dot over (ε)}₀: Reference strain rare    -   C: Material parameters measured at or below the transition        temperature    -   σ⁰ (ε^(−pl), θ): is the static yield stress    -   R({dot over (ε)}^(−pl)): is the ratio of the yield stress at        nonzero strain rate 10 the static yield stress (so that R({dot        over (ε)}₀)=1.0)

The elastic behavior of the material was defined with a hydrodynamicmaterial model, in which the pressure is defined as a function of thedensity and the internal energy.

Dynamic Failure Model for Lead Material

The Johnson-Cook dynamic failure model which is suitable for high-strainrate deformation of metals was used to define the lead failure in thehigh-speed ballistic impact simulation.

The model assumes that the equivalent plastic strain at the onset ofdamage. is a function of stress triaxiality and strain rate. The failureis assumed to occur when the damage parameter exceeds 1. The damageparameter w is defined as

$\omega = {\sum\left( \frac{{\Delta\varepsilon}^{- {pl}}}{\varepsilon_{f}^{- {pl}}} \right)}$

Where Δε^(−pl) an increment of the equivalent plastic strain is, ε_(f)^(−pl) is the strain at failure, and the summation is performed over allincrements in the analysis. The strain at failure, ε_(f) ^(−pl) isassumed to be dependent on a non dimensional plastic strain rate,

$\frac{{\overset{.}{\varepsilon}}^{- {pl}}}{\varepsilon_{f}^{- {pl}}};$

a dimensionless pressure deviatoric stress ratio, p/q where p is thepressure and q is the mises stress; and the non dimensional temperature{circumflex over (θ)}. The dependencies are from

$\varepsilon_{f}^{- {pl}} = {{\left\lbrack {D_{1} + {D_{2}{\exp\left\lbrack {d_{3}\frac{p}{q}} \right\rbrack}}} \right\rbrack\left\lbrack {1 + {d_{4}{\ln\left\lbrack \frac{{\overset{.}{\varepsilon}}^{- {pl}}}{{\overset{.}{\varepsilon}}_{0}} \right\rbrack}}} \right\rbrack}\left( {1 + {d_{5}\hat{\theta}}} \right)}$

The stress on armored plate is illustrated, the results shows when abullet gets fired from center of trough (6), the stress on armed plateis less than the stress on modular back stop, the said first impact zone(13) circumferentially oriented at a first angle from the horizontalzone has more stress and compared to one successive impact zone (14).

As the plates are stacked to form a rectangular block. This block willhave very high flexural bending strength compared to old design causingnegligible deflection. As the plates are stacked to form a rectangularblock. This block will have very high flexural bending strength comparedto old design causing negligible deflection. Irrespective of the bullethitting direction the deformation point is not constrained to singlelocation on the armor plate. It is distributed to two locations whichare at considerable distance. Final Bullet impinging load will bedistributed to minimum three to four plates.

If the plates wear further and make a cavity, the bullet goes inside thecavity and retards the speed of the bullet and stops. However, if cavitybecomes big removing the distorted bullet can be done by removing thetop plate.

The volume of the device has decreased nearly to ¼th compared to theprevious volume and the weight got decreased. Thickness of the armorplate can be increased to our convenience. As the plates are stacked,the self-weight of the plates and the long bolts which hold the platesin stacked manner will increase the compressive force making all thestacked plates behave like a single lumped block.

As the system is designed in modular cassettes, after the plates wear toconsiderable thickness, each module can be replaced with new cassettewithout disturbing the whole device.

All the possibilities of the bullet reverse travel were tested usingdynamic analysis simulation and is observed that the bullet cannottravel in reverse direction after hitting the target. This system wastested with SLR bullet of weight 11.5 g with speed of 850 m/s. KineticEnergy of the bullet is 4.15 kJ. When the bullet hits at bulls' eye(Case-1) the results show that the deflection on armor plate is 0.16 mmand could see elastic strains 0.00824 with stress of 633 MPa.

As the kinetic energy is 4154 J the total reaction force acting on theblock is 415.4 kN which is equal to 42.34 tonnes acting for 0.0117 secas a impulse shock. As the front nose cone of the SLR bullet is 0.5 mmthick with lead-antimony (Yield 15 MPa) content which is very soft instrength compared to steel (650 MPa) is smashed due to 0.5 mm thickcopper coated steel jacket which causes the surface area of the bulletto increase causing the impact to spread to larger area of the plate.

Analysis results suggest that the device (01) with modular backstop (7)can withstand a greater number of bullet shots before its failure due tomore thickness and high flexural bending strength. Its modular cassette(11) design will help us in replacing the distorted and deformed plates(12) easily.

Referring FIG. 4 a-4 b , Continuous firing of bullets within short timegenerates high temperatures and causes consequential material propertychanges of the back plates and leads to deformation in shape of theplates and finally allows penetration of bullets in to the back plates.Whereas in the present invention, the stacked armored plates each act asheat sink fin increases the surface area for heat dissipation.

As we know the thermal conductivity

${Q = \left( \frac{- {{KA}\left( {T_{2} - T_{1}} \right)}}{L} \right)};$

the thermal conductivity of the armored plates used in cassette typeconfiguration will increase due to increase in surface area of thearmored plates. The heat is dissipated due to conduction, and themodular backstop of the present invention will not deform due to heataccumulation as we see in the prior art bullet/projectile containmenttraps. Flexural bending strength of the modular backstop of the presentinvention is also managed due to high momentum of inertia in the bendingdirection.

Non linear impact dynamic analysis is performed to calculate velocitydegradation of bullets being dissipated with respect to guide plates(6). Many iterations are been performed for smooth velocity degradationand accordingly a profile of the modular backstop is evaluated as shownin FIG. 4 a -4 b.

Referring to FIG. 5 , a method of replacing cassettes (11) and/or theindividual armored plates (12) for deformation of the modular backstop(7) of the said bullet containment trap device (1) is disclosed.

In accordance with the exemplary embodiment of the present invention,the method comprises a first step of removing a plurality of long bolts(8) that locks a plurality of cassettes (11) formed of stacking multipleindividual armored plates (12) vertically and/or horizontally. Themethod comprises a second step of removing a back plate (18) and aplurality of side plates to get access to the said cassettes (11). Themethod comprises a third step of identifying a damaged cassette (11)from the lumped block to repair and replace the damaged cassette (11)and/or the individual armored plates.

In accordance with the exemplary embodiment of the present invention,the method comprises a fourth step of removing a plurality of cassettelocking bolts (8 a) to remove damaged armored plates (12) of the saidcassettes (11).

In accordance with the exemplary embodiment of the present invention,the modular backstop (7) of the said bullet containment trap device (1)allows cassettes (11) and/or the individual armored plates (12) withineach of the said cassettes (11) to be easily replaced and/or repairedfor deformation.

Thus, there is disclosed an improved bullet containment trap with amodular backstop. Those skilled in the art will appreciate numerousmodifications which can be made without departing from the scope andspirit of the present invention. The appended claims are intended tocover such modifications.

I/We claim:
 1. A bullet containment trap device (1) with a modularbackstop (7), wherein the device (1) comprises of: at least oneelectronic target assembly configured to project at least one targetplaced at a rear end of an open-ended bullet receiving chamber; thebullet receiving chamber (4) is supported by a plurality of supportingframes (2, 3); the said bullet receiving chamber (4) is backed with abullet's deceleration chamber (5) in a horizontal axis and or in avertical axis; the bullet fired compasses the bullet receiving chamber(1) while in contact with a plurality of boundary walls and enters aterminal part of said boundary wall over a throat (6) of a passagewayand moves through said throat (6) to dissipate on hitting a modularbackstop (7) of the said deceleration chamber (5); Characterized in thatthe said modular backstop (7) comprises a first impact zone (13)circumferentially oriented at a first angle from the horizontal zone ofbullet travel and extends to at least one successive impact zone (14);the said modular backstop (7) with at least two impact zones are made bystacking multiple individual armored plates (12) vertically and/orhorizontally in to a plurality of cassettes (11); the said cassettes(11) formed by stacking multiple individual armored plates (12) are heldvertically and/or horizontally to form the said modular backstop (7),wherein the said cassettes (11) are joined with long bolts (8 a) makingthe impinging loads of the bullet hitting the said backstop (7)distributed to multiple individual plates (12) of the said cassettes(11) closely stacked; and the said cassettes (11) and/or the individualarmored plates (12) within each of the said cassettes (11) are allreplaceable for deformation.
 2. The device (1) as claimed in claim 1,wherein the said device (1) is used for de-energizing and collecting thebullet fired along a substantially horizontal path of flight.
 3. Thedevice (1) as claimed in claim 1, wherein the said bullet that entersthe said deceleration chamber (5), even at a relatively low angle willmove along the chamber without being shattered or damaging the walls orthe modular backstop (7).
 4. The device (1) as claimed in claim 1,wherein the spent bullet ultimately falls off the modular backstop (7),and are flushed into a passageway and then into a collecting vessel(10).
 5. The device (1) as claimed in claim 1, wherein the modularbackstop (7) comprises very high flexural bending strength compared tomultilayered backstops.
 6. The device (1) as claimed in claim 1, whereinthe said cassettes (11) vertically held with support of long bolts (8)increases the compressive force making all the stacked plates behavelike a single lumped block.
 7. The device (1) as claimed in claim 1,wherein the deformation point is not constrained to single location onthe modular backstop (7) of the device, but is distributed to locationswhich are at considerable distance.
 8. The device (1) as claimed inclaim 1, wherein the said cassettes (11) have configurable armoredplates (12) and each plate has a configurable size.
 9. The device (1) asclaimed in claim 1, wherein the device (1) can also be rotated to beused in horizontal position by joining number of devices to form alarger device which can be used in both indoor and outdoor shootingranges.
 10. A method of replacing cassettes (11) and/or the individualarmored plates (12) for deformation of the modular backstop (7) of thesaid bullet containment trap device (1), wherein the method comprisessteps of: a. removing a plurality of long bolts (8) that locks aplurality of cassettes (11) formed of stacking multiple individualarmored plates (12) vertically and/or horizontally (07); b. removing aback plate (18) and a plurality of side plates to get access to the saidcassettes (11); c. identifying a damaged cassette (11) from the lumpedblock to repair and replace the damaged cassette (11) and/or theindividual armored plates; d. removing a plurality of cassette lockingbolts (8 a) to remove damaged armored plates (12) of the said cassettes(11); and e. the modular backstop (07) of the said bullet containmenttrap device (1) allows cassettes (11) and/or the individual armoredplates (12) within each of the said cassettes (11) to be easily replacedand/or repaired for deformation.